The Lithuanian defence ministry said its investigation is being complicated by the remote and swampy location of the crash, which is close to a lake near the town of Rėkyva.

However, parts of the aircraft wreckage have already been recovered using an Mi-8, it said.

The French air force confirmed that two of its Mirage 2000Cs had been taking part in a training sortie with the Lithuanian aircraft when the collision happened.

One of its fighters sustained some damage, but its pilot managed to land safely at Šiauliai.

Responsibility for NATO's air policing of the Baltic states will be transferred to the Royal Danish Air Force on 2 September, with four of its Lockheed Martin F-16 fighters having landed in Šiauliai on 31 August.

The service will assume the duties held by the French air force since April, which include holding two aircraft at 15-minute readiness to respond to suspicious aircraft movements or airspace incursions.